PHOENIX — Infielder Jonathan Herrera, who is attracting some mild trade interest, will travel to Reno Thursday and begin a rehab assignment Friday, playing five innings. Antibiotics have healed a staph infection in his left wrist. Texas is among the teams looking for a backup shortstop.

Pitcher Jhoulys Chacin will throw another side session at Coors Field on Thursday. He continues to make progress after missing several months with a nerve irritation in his right pectoral muscle. If Chacin does well, and throws at 100 percent with no pain, he will begin a long-anticipated rehab assignment.

Two-time all-star shortstop Troy Tulowitzki is hitting off a tee and doing light running work, but there’s no timetable for his return. He has told The Post repeatedly that he will play again this season. However, he must be 100 percent for that to happen. The Rockies aren’t going to risk an injury that would affect his offseason training.

Out with an irregular heartbeat, infielder Chris Nelson visited a cardiologist Wednesday. If cleared, he will slowly resume workouts this weekend.

In other news: Drew Pomeranz threw a side side session Wednesday and had no pain in his previously sore left biceps. He will start Friday at home against the Reds, pushing Christian Friedrich to Saturday and Jonathan Sanchez to Sunday. Because of the extra rest, Jeff Francis, tonight’s starter, will be allowed to approach 90 to 100 pitches if effective. The Rockies have won seven of his last eight starts.

Carlos Gonzalez is getting a planned day off after struggling in this series.

PHOENIX — Jonathan Herrera landed on the disabled list with an infection caused by his watch. While amusing at first, it was no laughing matter. He was diagnosed with a staph infection that required IV and antibiotic treatment. The middle infielder is improving and performing baseball activities.

Herrera is attracting trade interest. The Rangers have checked in on the infielder as they are looking for a backup shortstop.

Infielder Chris Nelson will visit a cardiologist Wednesday. If he checks out fine — he was placed on the disabled list with an irregular heartbeat — NElson will gradually begin activity. The former first-round pick had finally earned a starting job before an twisted ankle and heart issue derailed him. The Rockies, understandably, will proceed slowly with Nelson.

Rockies teammates were surprised and concerned when they heard of infielder Chris Nelson’s condition Monday. He left Coors Field prior to batting practice and was hospitalized with an irregular heartbeat. He remained on an IV drip late Monday.

“What they are doing is taking a period of time, X number of hours for the opportunity for his heart to go back into rhythm on its own. If it doesn’t, there will be a procedure sometime (Tuesday) where they have to shock the heart back into rhythm,” manager Jim Tracy said.

His teammates had no idea anything was wrong until he was absent during the team’s pregame stretch.

“I figured he was out taking groundballs or doing some extra hitting,’’ said Dexter Fowler, who lockers by Nelson. “I texted him, but haven’t heard back. We will be praying for him.’’

For Thursday afternoon’s series finale against the Nationals, the Rockies have first baseman Todd Helton hitting cleanup, followed by third baseman Chris Nelson hitting fifth.

There are reasons behind the unconventional starting nine. Jordan Pacheco is resting a strained quadriceps muscle that has been bothering him, off and on, for the better part of a month. Pacheco should be back in the lineup on Friday.

Michael Cuddyer, just 2-for-12 on the current homestand and his average down to .256, is getting a day off to regroup.

Michael Cuddyer, who blasted his second grand slam of the season Wednesday night, is taking over as the Rockies’ cleanup hitter as Troy Tulowitzki heads to the 15-day disabled list with a groin injury.

“Michael Cuddyer is the guy that makes the most sense to put in that spot behind Carlos Gonzalez,” manager Jim Tracy said this afternoon. “Will that be the same four or five days from now? I don’t know. But what we need from that spot is consistency.”

What Tracy means is that the Rockies need is an accomplished hitter in the No. 4 hole so teams can’t pitch around the dangerous CarGo, who hit three homers Wednesday night and leads the National League in slugging percentage (.629) and total bases (117) entering tonight’s game.

Trying to condense the Rockies’ Wednesday is like trying to stuff a bowling ball into a Ziploc bag. It began with the franchise cutting ties with Jamie Moyer, continued with three home runs from Carlos Gonzalez, Josh Outman landing in the rotation and concluded with Troy Tulowitzki sounding less-than-optimistic about avoiding the disabled list after re-injuring his left groin.

Tulowitzki limped through the clubhouse late Wednesday night, favoring the left leg he hurt bursting out of the batter’s box in his last at-bat. He exited the game, and admitted that the injury was much worse than when he first hurt the leg on the second day of the season in Houston turning a double play.

“For me to say that, obviously, it’s a concern,” said Tulowitzki, who has lifted his average to .287 with 14 hits in his last 36 at-bats, including four doubles, four home runs and 11 RBIs. “I will see how it feels tomorrow. If it’s still really sore, then maybe I need an MRI and it’s a DL situation. Obviously, I am going to miss a few days at least. I want to stay off the DL. But if I can’t go, I can’t go.”

Rockies fans hoping to see a quick fix for lefty Drew Pomeranz are going to be disappointed.

It looks like it’s going to be a while before the prospect/project can return to the big-league club and add stability to their reeling rotation. While Pomeranz’s raw numbers look good, he is still struggling with mechanics and pitch command.

Making his third start for Triple-A Colorado Springs on Thursday, Pomeranz (2-1, 1.23 ERA) lost for the first time, allowing six runs (four unearned) in three innings of work as Oklahoma City beat the Sky Sox 7-4.

There was a bit of good news and a lot of bad news for Triple-A Colorado Springs in it’s 9-5 loss to Oklahoma City on Tuesday.

The good: Rockies Third baseman Chris Nelson, on a rehab assignment as he comes back from an injured wrist, had three hits, including a double, and scored two runs. Left fielder Andrew Brown also had three hits, including a double, with two RBIs.

The bad: Lefty reliever Rex Brothers, in his first start since being sent down last weekend, continues to struggle with command. In two innings, he walked two, allowed two hits and gave up a run. He did strike out five, showing that his dynamic stuff is very effective — when he can harness it.

Jordan Pacheco has got the March thing down. For the past two years he’s been a spring training superstar, which is baseball’s equivalent of being a a great warmup band. Now, he’s got a shot to show he can stick in the lineup at third base.

The Rockies believe the former New Mexico star will hit — he’s done it at every minor league level and has RBIs in his past two games — but need him to make the routine play at a position he’s learning in real time. Manager Jim Tracy has seen improvement, and indicated that Pacheco will start with Chris Nelson on the disabled list, casting Jonathan Herrera as a utility player.

“(Pacheco’s) not a slugger. But he’s a hitter. He’s going to give you good at-bats. And we aren’t asking him to be (Hall of Famer) Brooks Robinson over there at third,” Tracy said. “He’s getting better reads. He’s showing improvement.”

Pacheco is starting today in the finale of the two-game series with the slumping Diamondbacks. Michael Cuddyer is resting. “He’s tired. He’s not going to tell me he needs a day, and I respect that. But I can go by what my eyes are telling me. And he needs one,” Tracy said. That frees spots for both Tyler Colvin, who has hit safely in 11 of 14 starts, and Dexter Fowler, who went 3-for-3 in Wednesday’s win.

Then-Rangers infielder Jorge Cantu gestures "antlers" for TCU in the Horned Frogs' game against Air Force in 2010.

With third base unsettled, the Rockies are kicking around the idea internally of pursuing free agent Jorge Cantu. The veteran could serve as Triple-A depth, and has a history with the Rockies.

He played briefly for the Sky Sox last season, hitting .280 with 11 extra-base hits and 18 RBIs in 30 games. Cantu opted out of his contract with the Angels this week after batting .291 with four home runs for their Triple-A affiliate.

The Rockies are weighing Cantu against their current options at third base, according to a team official. Cantu would have to be able to play third to fit at either Triple-A or the big leagues, and the team is still researching that question.

DENVER — Jonathan Herrera has been productive as a starter, and with Chris Nelson’s wrist still sore, the Rockies’ infielder finds himself at third base again. Over his last six starts, Herrera is 8-for-22 with a home run, double and three RBIs.

Nelson is available to play. He has hit well at Coors Field, but has struggled on the road and against right-handed pitching (3-for-34). The Dodgers are starting righty Aaron Harang tonight followed by a pair of lefties, Ted Lilly and Clayton Kershaw.Read more…

Dexter Fowler hasn’t been much of a table setter for the big bats in the Rockies’ order, so the center fielder finds himself hitting eighth in tonight’s game vs. the Mets. Fowler has been in the No. 2 hole most of the season.

In another move, utility man Jonathan Herrera starts at third base in front of Chris Nelson. Nelson still has a tender wrist after tweaking it on a diving play in Pittsburgh. Plus, Nelson was 0-for-13 on the recent six-game road trip.

HOUSTON — The grass is green, expectant at Minute Maid Park. The bunting hangs from the rafters, gently blowing in the wind. In a world doused in cynicism, selfishness and controversy, opening day provides a brief respite from reality.Read more…

Hits: Tyler Colvin, who’s had a great spring, is starting to put the heat on Dexter Fowler in center. Colvin hit two moon shots Sunday, the first one about 450 feet, the second one, to dead center, about 430 feet. The first homer was a two-run homer off Ubaldo Jimenez in the third inning. … Chris Nelson, who will start at third base on opening day, hit a two-run blast off Jimenez in the third.

Misses: Troy Tulowitzki, obviously, did not have a good day after getting drilled by former teammate Ubaldo Jimenz in the first inning. Tulo had to leave the game with a left elbow injury. … Right-hander Jeremy Guthrie, making his final start before Friday’s regular-season opener at Houston got rocked hard by the Indians. Guthrie pitched three innings, giving up four runs on six hits, with a homer. Worst of all, he walked four. Guthrie finished with a 4.79 ERA. … Alex White, who began the spring as a potential starter, got roughed up in his two innings for work as a reliever. White gave up five runs on four hits, including a grand slam Shelly Duncan in seventh. White walked two.

On Deck: The Rockies wind down spring training Monday with the first of three games against the Mariners at Peoria. Jamie Moyer, the 49-year-old left who’s won a job in the rotation, starts for the Rockies. Right-hander Felix Hernandez starts for Seattle.

Hits: Eric Young Jr. and Jonathan Herrera delivered back to back two-out singles in the first inning. Young Jr. entered the at-bat 1-for-12 and is now 2-for-14. He’s out of options and remains potential trade bait. … Matt Belisle and Rex Brothers, the club’s top two setupmen, have not allowed a run in eight combined innings. … Chris Nelson, also out of options, singled and stole second in the top of sixth inning. He’s competing for a utility spot with Herrera. … DJ LeMahieu had a diving play at shortstop, and delivered an RBI single and stolen base in the ninth inning. … Joe Gardner impressed Jim Tracy with his ninth inning. He compared to him to former Dodgers’ reliever Paul Quantrill.

Misses: Left-hander Drew Pomeranz exited after two innings with tightness in the gluteus muscle around his hip. He said he could have pitched through it, but “it wasn’t worth the risk.’’ Pomeranz threw 22 strikes in 34 pitches, feeling as sharp as he has all spring. “I am kind of (upset) I had to come out,’’ he said. Pomeranz has strung together seven scoreless innings, allowing just three hits. He’s in line to pitch again Sunday, but treatment will determine if that start is pushed back. … Jordan Pacheco forgot his jersey leaving wearing No. 98. … Rob Scahill labored through three innings, giving up five hits, and two runs. The damage could have been much worse if not his strike out of Matt Angle to end the seventh.

On Deck: At Rangers, 2:05 p.m.; vs. Diamondbacks, 8:05 p.m.. Several of the regular position players are expected to be in the lineup against Texas, including Todd Helton, Troy Tulowitzki, Marco Scutaro and Jason Giambi, who will DH. Tyler Chatwood starts. In the night game, Juan Nicasio makes his second start and Michael Cuddyer will make his first appearance at first base. … Closer Rafael Betancourt and Matt Reynolds will follow. Catcher Ramon Hernandez is scheduled to start.

SCOTTSDALE — Casey Blake was scratched from Monday’s lineup with a stiff neck, continuing a slow spring training for the 38-year-old.

The injury is not related to neck surgery he underwent Sept. 6, according to a source. Blake was signed to buy time for developing prospect Nolan Arenado. Blake is 0-for-9 with four strikeouts this spring. Arenado has struggled this week, and will likely need a little more minor league seasoning after not playing about the Class-A level.

If Blake doesn’t heal and produce, the Rockies could choose from a number of candidates at third base, including Brandon Wood, who’s starting today, Jordan Pacheco and Chris Nelson

SCOTTSDALE — Nolan Arenado looked over at Jamie Moyer’s locker and couldn’t help but wonder.

“Man he’s been doing this for a long time. It’s unreal,” Arenado said. “I was just talking about this with my trainer. He’s old enough to be my dad, and he’s out here competing. It’s great to see.”

Age is just a number to Arenado and Moyer. At 20, Arenado doesn’t see any reason why he can’t break camp with the Rockies despite finishing last season in Class-A Modesto.

“I am here to win a spot, that’s how I am looking at it,” said Arenado, who was the Arizona Fall League MVP, training at Salt River Fields and occupying Todd Helton’s locker. “I want to be on this team and help us win.”

Patrick, a third-generation Colorado native, is back for his second stint covering the Rockies. He first covered the team from 2005-2009, helping chronicle “Rocktober” in 2007 and also following the team’s playoff run in 2009.

Nick Groke has worked at The Denver Post since 1997, as a sports reporter, city reporter, entertainment writer and digital editor and producer, among other newsroom posts. He also writes regularly about boxing, soccer, MMA and NASCAR.